I own a 2007 Mazda3 2.0 that usually gets a serving of either Motorcraft or Kendall 5w20 synthetic blend for 5K OCI. I went out of the norm this time and decided to use Valvoline conventional 5w20 for the first time. I know its probably all in my head but I have to say I can honestly feel a difference. The car runs smoother and is definitely a lot quieter using Valvoline. I might have to change to Valvoline from now on.